This disclosure relates to novel, stable aqueous dispersions of solid particles, the crosslinked polymeric dispersants that produce the stable aqueous particle dispersions, the process of making the same and the use thereof in ink jet inks.
Aqueous dispersions of solid particles are known in the art and have been used in various applications such as, for example, inks for printing (particularly ink jet printing); waterborne paints and other coating formulations for vehicles, buildings, road markings and the like; cosmetics; pharmaceutical preparations; etc. For examples, pigment particles are typically not soluble in an aqueous ink vehicle; it is often required to use dispersing agents, such as polymeric dispersants or surfactants, to produce a stable dispersion of the pigment in the aqueous ink vehicle.
An application of the present disclosure relates to an ink (printing liquid) useful for writing utensils such as aqueous ball point pens, fountain pens and felt-tip pens; continuous and on-demand type inkjet printers of a thermal jet type, a piezo type and the like; and an inkjet printing method employing the ink.
There has been effort in the art directed at improving the stability of the dispersions so that the particles are less likely to settle out of the vehicle under defined set of conditions. The effort to improve dispersion stability to date has included improvements in the processes used to make the dispersions, the development of new dispersants and the exploration of the interaction between dispersants and particle, and between dispersants and aqueous ink vehicle. While much of the effort has general application at improving dispersion stability, some of that effort has not found utility in particular applications. For example, the pigment dispersions used in ink jet printing applications have very unique and demanding requirements. It is critical that ink components comprising pigment dispersion remain stable, not only in storage but also over repeated jetting cycles.
There continues to be a need for highly stable, higher-quality and different property inks for inkjet ink applications. Although improvements in polymeric dispersants have significantly contributed to improved inkjet inks, the current dispersants still do not provide inks with requisite stability, optical density and chroma needed for emerging ink jet applications. The present invention satisfies this need by providing a dispersion stabilized by a structured vinyl polymer dispersant having crosslinkable moieties crosslinked with a crosslinking agent.